Thymeleaf Neither BindingResult nor plain target object for bean name 'person' available as request attribute

You forgot to add BindingResult after your @ModelAttribute :

@RequestMapping(value="/person", method=RequestMethod.POST)
public String contactSubmit(@ModelAttribute Person person, BindingResult bindingResult, Model model) {
    if (bindingResult.hasErrors()) {
        //errors processing
    }  
    model.addAttribute("person", person);
    return "result";
}

I'm already have answered to question like this :

• html form validation using thymeleaf not working spring boot

Model attribute has to be initialized (using GET method) before calling post method. In your case you need one more method in controller which does model.addAttribute("person",new Person()); and it has to be called before post.

Refer below link: https://spring.io/guides/gs/handling-form-submission/ OR http://forum.thymeleaf.org/Neither-BindingResult-nor-plain-target-object-for-bean-name-miniDoniie-available-as-request-attribute-td4027859.html

It has GetMapping as well as PostMapping in controller.